Cellular aging, especially the aging of skin cells, has been extensively studied. One of the most important factors in cellular aging is the formation and accumulation of free radicals within cells. Cellular aging is usually fought by protecting the skin by blocking mechanisms against UVA/UVB radiation and against reactive oxygen species (ROS) or oxygen free radicals, which are generated by exposure to sunlight and oxygen, their formation being catalyzed by pollutants and enhanced by the presence of traces of ozone. An important group of free radicals are the Reactive Carbonyl Species (RCS) generated in oxidative biological processes such as lipid peroxidation, which are one of the factors involved in accelerated skin aging, skin aging by UV radiation and erythema of the skin. In the context of this invention, the term “aging” refers to changes in the skin that occur with age (chronoaging) or sun exposure (photoaging) or environmental agents such as tobacco smoke, extreme cold conditions of weather or wind, chemical pollutants or pollution, and includes all external visible changes as well as those perceptible by touch, for example and without limitation thereto, the development of discontinuities in skin such as wrinkles, fine lines, cracks, irregularities or roughness, enlarged pores, loss of elasticity, loss of firmness, loss of smoothness, loss of recovery from deformation, sagging of the skin such as sagging of the cheeks, the appearance of bags under the eyes or the appearance of jowls, inter alia, changes in skin color such as spots, redness, dark circles, bags under the eyes or the emergence of hyperpigmented areas such as age spots or freckles, inter alia, abnormal differentiation, hypercornification, elastosis, keratosis, hair loss, appearance of orange-peel skin or cellulite, loss of the structure of collagen and other histological changes of the stratum corneum, the dermis, the epidermis, the vascular system, such as the emergence of spider veins or telangiectasia, or of the tissues close to the skin, inter alia.
At molecular level, the RCS are responsible for, among other processes, for DNA damage, degradation of proteasomes and alteration of intra and extracellular proteins [Degenhardt T P, Brinkmann-Frye S R, Thorpe S R and Baynes J. W. (1998) in The Mailard Reaction in Foods and Medicine, J. O'Brien, Nursten H E, Crabbe M J C and Ames J M, eds, pp 3-10, The Royal Society of Chemistry, Cambridge, UK]. These species include unsaturated aldehydes and the peroxidation of polyunsaturated fatty acids in the form of α aldehyde, β-unsaturated, harmful and toxic cells. Aldehydes are also formed in glycation reactions, and by the influence of different pollutants. Some of the major aldehydes formed by lipid peroxidation are malondialdehyde (MDA), acrolein, 4-hydroxy 2-nonenal (HNE), 2-nonenal (NE), glyoxal and methylglyoxal, formed by the influence of different pollutants, formaldehyde, acrolein and crotonaldehyde. These aldehydes, due to their electrophilic nature, are highly reactive with cellular nucleophiles such as glutathione, protein side chains of cysteine, lysine and histidine, and nucleic acids [Liu Q, Raina A K, Smith M A, Sayre L M and Perry G. (2003) “Hydroxynonenal, toxic carbonyls, and Alzheimer disease” Mol. Aspects Med 24:305-313]. These aldehydes not only degrade key components such as cellular DNA, but their effect is compounded because the proteins involved in the endogenous DNA repair mechanisms are also damaged, losing their functionality.
In particular, HNE is a metastable species, present in relatively high concentrations in biological tissues, which can easily spread from their place of origin and thus can propagate oxidative damage by acting as a secondary toxic messenger [Uchida K., Shiraishi M., Naito Y, Torii Y, Nakamura Y. and Osawa T. (1999) “Activation of stress signaling pathways by the end product of lipid peroxidation. 4-hydroxynonenal is a potential inducer of intracellular peroxide production “J. Biol Chem 274:2234-2242]. Acrolein, in turn, is an unwanted and unstable byproduct caused by overheated organic matter, and is present as a contaminant in the environment, for instance formed by the incomplete combustion of plastic and consumption of tobacco [Uchida K., Kanematsu M., Morimitsu Y, Osawa T., Noguchi N. and Niki E. (1998) “Acrolein is a product of lipid peroxidation reaction. Formation of free acrolein and its conjugate with lysine residues in oxidized low density lipoproteins, “J. Biol Chem 273:16058-16066]. In the natural protection mechanisms of cells the RCS are captured by certain scavenger substances in cells, such as glutathione, in order to avoid toxic or harmful effects on the cell, specifically damage to proteins and to cellular DNA. However, this scavenging of RCS cells by natural mechanisms does not occur properly when the cell is subjected to UV radiation; this circumstance is common, for example, in dermal cells. This alteration of the natural protection mechanisms also involves a decrease in the efficacy of DNA repair mechanisms, because the proteins involved in repair processes are damaged. Therefore, there is a need to assist the scavenging of the RCS in cells exposed to UV radiation. In this sense, the administration of sequestering substances has been suggested, in order to help catch these RCS to prevent degradation of cell proteins and DNA, essential components for cellular viability, as well as to enhance the efficacy of the DNA repair mechanisms. The scavenging will therefore reduce, delay and/or prevent symptoms of aging and/or photoaging.
A secondary effect of the treatment of cellulite with lipolytic agents is the rapid generation of fatty acid oxidation which ends up producing an increase in skin RCS. The toxic effect of these RCS causes premature aging of the treated skin, with a loss of elasticity that involves a persistent orange-peel appearance of the cellulite-affected area despite treatment. In this sense, the administration of sequestering substances has been suggested, in order to help scavenging these RCS to prevent their toxic or harmful effects. This scavenging will, therefore, improve the appearance of cellulite-affected skin and help prevent and/or treat cellulite.
There are several studies on the administration of certain substances with regard to their ability to scavenge RCS in cells, especially of carnosine and glycyl-histidyl-lysine (GHK) tripeptide. Carnosine has demonstrated an acceptable scavenging efficiency for two aldehydes, HNE and acrolein. However, carnosine has the drawback of being extremely labile to enzymatic action of specific enzymes such as carnosine [Pegova A., Abe H. and Boldyrev A. (2000) “Hydrolysis of carnosine and related compounds by mammalian carnosine” Comp. Biochem. Physiol. B. Biochem. Mol. Bio. 127:443-446]. Moreover, one of the direct decomposition products of carnosine is histidine, which can easily turn into histamine in the body and which is involved in allergic processes.
With regard to GHK tripeptide, some of its applications in its form of complexes with metals, especially copper, have been described. Thus it has been found that such complexes are involved in the regeneration and repair of some types of tissues in mammals, especially in the sense of accelerating wound repair, increasing re-epithelialization of the skin, increasing skin thickness, increasing the subcutaneous fat layer, increasing the size of hair follicles, curing stomach ulcers, etc. Its RCS scavenging efficiency has also been described, as well as the inhibition of cell death induced by exposure to RCS [Cebrian J., Messeguer A., Facino R M and Garcia Anton J. M. (2005) “New anti-RNS and-RCS products for cosmetic treatment” Int J. Cosmet. Sci 27:271-278], and its benefit as an adjunct in the treatment and/or prevention of cellulite [EP1611898 B1 Lipotec]. However, the chemical stability of tripeptide is low, rapidly degrading in solution, which requires an active stabilization protocol in cosmetic and pharmaceutical formulations.
Therefore, there is a need to find new RCS scavengers more stable than carnosine and GHK.
Body Odor
The nature of the odor emitted by the human body is influenced not only by endogenous factors such as genetic makeup or the pathologies presented by the human body, but also by factors such as lifestyle, food intake, smoking and bathing frequency [Labows J N (1979) “Human odors” Perf. 4:12-17 flavor, Senol M. and Fireman P. (1999) “Body odor in dermatologic diagnosis” Cutis 63:107-111]. Components of the scent given off by the human body have been identified, mostly volatile aldehydes formed from fatty acids and their esters secreted by various human organs and/or cells. The components of body odor are not constant throughout the different stages of life. Specifically, the smell of people of middle and advanced age is due mostly to aldehydes of unsaturated fatty acids such as 2-nonenal or 2-octenal, formed from 9-hexacedenoic acid, which is found primarily in the sebaceous secretions of people of middle and advanced age and is responsible for the unpleasant, fatty and rancid body odor that is associated with aging [S. Haze, Y. Gozu, S. Nakamura, Y. Kohno, K. Sawano, H. Ohta and K. Yamazaki (2001) “2-Nonenal newly found in human body odor tends to increase with aging,” J. Invest. Dermatol. 116:520-524]. These α and β unsaturated aldehydes are Reactive Carbonyl Species (RCS) generated in the fat and skin during the process of lipid peroxidation incurred by fatty acids in situations of oxidative stress.
The cosmetics industry has employed various strategies for mitigating this odor, which are based on masking body odor with a fragrance or perfume or employing physical absorbents to prevent the dispersal of the scent. Neither of these strategies solves the problem of body odor as they do not inhibit the formation of odor per se and furthermore entail that, collaterally, the use of perfumes generates more aggressive odors when the different aromatic compounds are mixed or that the use of absorbents such as cyclodextrins or charcoal does not yield immediate results. A different strategy is based on inhibition of the generation of body odor and involves the use of antioxidants and/or antibacterial agents. These agents are effective in inhibiting the generation of odor, but it is known that their continued use can cause allergies.
Thus, there is a need for new substances capable of inhibiting body odor, specifically body odor caused by the generation of RCS and associated with aging. Patent application DE 102 37 458 A1 describes the use of carnosine as an inhibitor of body odor caused by the generation of RCS. Patent EP 0 955 035 B1 describes the use of antioxidants, lipoxygenase inhibitors and/or antibacterial agents with substances capable of masking body odor caused by the generation of RCS. Patent application JP 2001254274 A describes tissues functionalized with agents for inhibiting body odor caused by RCS. U.S. Pat. No. 6,497,862 B1 describes the use of trehalose and/or maltitol as agents for inhibiting body odor caused by the generation of RCS. GHK tripeptide and carnosine and their derivatives are the only peptides able to scavenge RCS and thus are potent anti-aging agents and inhibitors of body odor. However, these two peptides have the stability problems mentioned above.
Thus, there is a need for new effective peptides capable of scavenging RCS and solving the stability problems known in the state of the art.